In motor vehicles, especially commercial vehicles with an automated gearbox, an actuating device is often used such that various operating modes of the motor vehicle can be selected, such as “drive”, “neutral”, “park” or “maneuver” or “creep”. By selecting the “maneuver” or “creep” operating mode, the driver is enabled to shift the transmission to an operating mode in which the clutch can be actuated particularly gently. In addition, a drive engine of the motor vehicle in this operating mode, for example an internal combustion engine, can be controlled in such a manner that a change of the drive train torque only takes place with small torque or speed gradients.
DE 101 05 749 A1 discloses a method for easier maneuvering of a commercial vehicle. The commercial vehicle comprises an automated transmission and an automated clutch, as well as a switching device. With the switching device, for example a rotary selector switch, the motor vehicle operating conditions forward-drive “D”, neutral “N” and reverse “R” and maneuvering settings “RM, DM” or maneuvering assistance settings “RMB, DMB” can be selected. When the maneuvering mode is activated, then depending on the position of the accelerator pedal and the loading condition of the vehicle, the clutch and the service friction brake are automatically actuated at the same time and in harmony with one another.
DE 100 16 582 A1 discloses a motor vehicle which comprises a transmission, an automated clutch, a control device, an accelerator pedal, a brake pedal and an actuating device which is used to activate a creep process. From DE 100 16 582 A1, various configurations of the actuating device are known with which a creep process can be initiated. For example, the actuating device can be designed as a manually operated rotary selector switch which, in addition to the usual settings for the driving modes of the automatic transmission, can adopt two further stable positions in which the creep mode can be engaged either for forward or for reverse driving.
In the “maneuver” or “creep” operating mode, the clutch and/or the drive engine is controlled by a drive or accelerator pedal position determined by the driver of the vehicle. For example, in the “maneuver” or “creep” operating mode the drive or accelerator pedal deflection can be adapted so that in the “maneuver” or “creep” mode a larger actuation angle is permitted for a corresponding fuel injection quantity than in the “drive” operating mode. Thus, in the “maneuver” or “creep” mode, at the same deflection angle of the drive or accelerator pedal, the motor vehicle can be moved at a lower speed. If the motor vehicle is being operated in the “maneuver” or “creep” mode and the operating mode is changed to “drive” using the actuating device, this can result in an acceleration of the vehicle without the driver having changed the position of the drive or accelerator pedal, since the clutch and/or the drive engine are no longer actuated as gently as in the “maneuver” or “creep” operating mode.
Corresponding behavior is observed when the actuating device is switched from the “drive” to the “maneuver” or “creep” operating mode. If the motor vehicle is being operated in the “drive” mode and the actuating device is changed to the “maneuver” or “creep” mode, then in accordance with the “maneuver” or “creep” mode, the drive train torque is reduced. In situations, such as driving or starting on a slope, this, in turn, can cause the vehicle to stop accelerating. In extreme situations, it can even happen that the vehicle rolls backward without the driver having changed the pedal angle of the drive or accelerator pedal, because of the operating mode change from “drive” to “maneuver” or “creep”.
Similar behavior occurs during a starting process if the actuating device is at “neutral” on the way to selecting an operating mode and the vehicle's driver actuates the drive or accelerator pedal and then moves the actuating device to another operating mode, i.e., selects a gear. This situation leads to engaging of the clutch without a change of the drive pedal position by the vehicle's driver having taken place, which can result in undesired starting of the motor vehicle.
In a motor vehicle with an automated clutch, a driver of the vehicle can usually only initiate clutch actuation via the drive or accelerator pedal or the brake pedal. Thus, actuation of the clutch, by virtue of a situation as described earlier, leads to unexpected engaging or disengaging of the clutch, where safety-critical driving situations can arise, since in the situations described earlier, neither the drive or accelerator pedal nor the brake pedal are actuated appreciably by the vehicle's driver.
The purpose of the present invention is to indicate a method for controlling a motor vehicle with an automated clutch, by way of which the disadvantages of the prior art are minimized or eliminated and which enables safe operation of the automated clutch.